Generic pairs of SU-rank 1 structures

For a supersimple SU-rank 1 theory T we introduce the notion of a generic elementary pair of models of T (generic T-pair). We show that the theory T^* of all generic T-pairs is complete and supersimple. In the strongly minimal case, T^* coincides with the theory of infinite dimensional pairs, which was used in (S. Buechler, Pseudoprojective strongly minimal sets are locally projective, J. Symbolic Logic 56(4) (1991) 1184–1194) to study the geometric properties of T. In our SU-rank 1 setting, we use T^* for the same purpose. In particular, we obtain a characterization of linearity for SU-rank 1 structures by giving several equivalent conditions on T^*, find a “weak” version of local modularity which is equivalent to linearity, show that linearity coincides with 1-basedness, and use the generic pairs to “recover” projective geometries over division rings from non-trivial linear SU-rank 1 structures.     

A structural framework for the design of integrated environmental and land-use planning optimization models

This study presents a structural framework for analyzing land-use/environmental interactions and formulating planning models accounting for these interactions. A general conceptual planning model is first developed. Its applicability is illustrated through a review of major environmental pollution transfer models, and through the development of a prototypical model that is progressively expanded to account for centralized treatments, transfer modifications, short-term and long-term dynamics, and the stochasticity of the environment.     

Learning to align organizational design and data

The relationship between organizational learning and organizational design is explored. In particular, we examine the information processing aspects of organizational learning as they apply to a two-valued decision making task and the relation of such aspects to organizational structure. Our primary contribution is to extend Carley's (1992) model of this process. The original model assumes that all data input into the decision making processes are of equal importance or weight in determining the correct overall organizational decision. The extension described here allows for the more natural situation of non-uniform weights of evidence. Further extensions to the model are also discussed. Such organizational learning performance measures provide an interesting framework for analyzing the recent trend towards flatter organizational structures. This research suggests that flatter structures are not always better, but rather that data environment, ultimate performance goals, and relative need for speed in learning can be used to form a contingency model for choosing organizational structure.     

An integrated FMS design procedure

This paper considers the problem of the design of an FMS system. An integrated design procedure is outlined, which involves three stages — planning, design and implementation. Within each stage the design decisions to be made are discussed, together with the techniques and skills required to complete each design stage. At each stage, reference is made to the views of other designers and researchers. Finally, the procedure is illustrated through a case study of a miniature FMS designed and installed at the Cranfield Institute of Technology.     

Towards integrated design and analysis

A systems analysis technique is used to investigate and better understand the processes involved in finite element modelling. Two different starting points are considered: engineering drawings and solid models. The breakdown of activities involved in finite element analysis from a solid model is used as a requirements definition and functional specification for software tools to facilitate automation of finite modelling and eventual integration of design and analysis.     

Simultaneous engineering approach to an integrated design and process planning

To support integration of design and process planning, a reference model has been developed. This reference model represents the basis for a new methodology for integrated design and process planning which enables a Simultaneous Engineering approach in the early stages of product development. The reference model consists of four partial models. These are the activity model, the information model, the technical system model and the model of integrating methods. Using these models, the methodology enables a concurrent processing of design and process planning activities with regard to different components of a product. Furthermore, the methodology covers planning methods as well as execution methods, to support early transmission of information to downstream activities and a feedback of information to upstream activities within the process chain of design and process planning.     

Optimization of structural design

Typical problems of optimal structural design are discussed to indicate mathematical techniques used in this field. An introductory example (Section 2) concerns the design of a beam for prescribed maximal deflection and shows how suitable discretization may lead to a problem of nonlinear programming, in this case, convex programming. The problem of optimal layout of a truss (Section 3) is discussed at some length. A new method of establishing optimality criteria (Section 4) is illustrated by the optimal design of a statically indeterminate beam of segmentwise constant or continuously varying cross section for given deflection under a single concentrated load. Other applications of this method (Section 5) are briefly discussed, and a simple example of multipurpose design (Section 6) concludes the paper.     

Using data mining to identify structural rules in proteins

The progress in bioinformatics and biotechnology area has generated a huge amount of sequences that requires a detailed analysis. There are several data mining techniques that can be used to discovery patterns in large databases. This paper describes the development of a tool/methodology to extract hydrophobicity patterns/profiles that archives a specific secondary structure in proteins. The results indicate that association rules can be efficient method to investigate this kind of problem. This work contributes for two areas: prediction of protein structure and protein folding.     

Application of an anisotropic growth formulation to computational structural design

Common structural optimisation problems consist of problem-specific objective functions which have to be minimised mathematically with respect to design and state variables taking into account particular constraints. In contrast to this, we adopt a conceptually different approach for the design of a structure which is not based on a topology-optimisation technique. Instead, we apply a one-dimensional energy-driven constitutive evolution equation for the referential density–originally proposed for the simulation of remodelling effects in bones–and embed this into the micro-sphere-concept to end up with a three-dimensional anisotropic growth formulation. The objective of this contribution is to investigate this approach with emphasis on its application to structural design problems by means of two three-dimensional benchmark-type boundary value problems. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optimal design of multi-purpose structures

The paper presents the optimal (maximum transverse stiffness) design of an elastic, simply supported member of given volume that is to serve as a beam or as a column at different times during its design life. The optimal design can be interpreted in two ways. It is the design that has the maximum Euler buckling load in column action, subject to a prescribed maximum deflection in beam action under a uniformly distributed load; it is also the design that has the least deflection at midspan under a uniformly distributed load, subject to a lower limit on its buckling load in column action. The effectiveness of the optimal design is judged by comparing it with a prismatic bar of the same volume.The author is grateful to Professor W. Prager for suggesting several improvements to an earlier version of the paper.     

Issues dedicated to Alexander M. Ostrowski

Issues dedicated to Alexander M. Ostrowski     

An integrated model for logistics network design

In this paper we introduce a new formulation of the logistics network design problem encountered in deterministic, single-country, single-period contexts. Our formulation is flexible and integrates location and capacity choices for plants and warehouses with supplier and transportation mode selection, product range assignment and product flows. We next describe two approaches for solving the problem---a simplex-based branch-and-bound and a Benders decomposition approach. We then propose valid inequalities to strengthen the LP relaxation of the model and improve both algorithms. The computational experiments we conducted on realistic randomly generated data sets show that Benders decomposition is somewhat more advantageous on the more difficult problems. They also highlight the considerable performance improvement that the valid inequalities produce in both solution methods. Furthermore, when these constraints are incorporated in the Benders decomposition algorithm, this offers outstanding reoptimization capabilities.     

A computational study on the performance of artificial neural networks under changing structural design and data distribution

This paper provides the results of our computational studies on artificial neural networks (ANNs) under various structural design and data distributions. A two-group classification problem is investigated. Simulated data with varying kurtosis and variance are used to examine how the ANN performs with respect to certain structural design (size and addition of input and weight noise) characteristics. The results of our study indicate that additive noise, size, and data distribution characteristics play an important role in learning, reliability and predictive ability of ANNs.     

Optimal structural design for given deflection

Zusammenfassung Es wird ein Prinzip der stationären gegenseitigen potentiellen Energie aufgestellt für zwei Belastungssysteme eines elastischen Balkens veränderlicher Biegesteifigkeit. Aus diesem Prinzip wird eine hinreichende Bedingung für stationäres Gewicht eines Sandwichbalkens abgeleitet, wenn die von einer Belastung an einem bestimmten Querschnitt erzeugte Durchbiegung vorgeschrieben ist. Für statisch bestimmte Balken wird gezeigt, dass diese Bedingung ein globales Minimum des Gewichts sicherstellt. Anwendungsbeipiele und Erweiterungen werden besprochen.

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This research was supported in part (W. P.) by the U.S. Army Research Office, Durham.